The Effect of Bile Duct Obstruction on the Clearance of Circulating IgA Immune Complexes

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Abstract
The clearance of circulating IgA immune complexes following acute bile duct obstruction was investigated in this study. IgA immune complexes were formed in vitro from MOPC-315, an IgA M-component with anti-dinitrophenyl (DNP) specificity, and 125I-DNP10 bovine serum albumin (BSA). Eighteen hours after laparotomy during which the common bile duct was either identified only or identified and ligated, the IgA immune complexes were injected intravenously. Groups of bile duct-ligated and bile duct-patent rats were also injected intravenously with IgG anti-DNP-125I-DNP 10BSA immune complexes and 125I-bovine liver β-glucuronidase to assess the hepatic clearance of materials not dependent on an intact biliary system. Clearance of IgA immune complexes was delayed after bile duct ligation. Although the clearance of IgA immune complexes was delayed, only 10% of these complexes remained in the circulation at 3 hr. The clearance of IgG immune complexes and β-glucuronidase was not affected by ligation. These experiments demonstrate the physiologic importance of a patent bile duct in the normal clearance of IgA immune complexes in the rat. The observation that clearance is delayed, but not completely inhibited by bile duct ligation suggests that alternate mechanisms exist for removing IgA immune complexes from the circulation.